From 443069282603c4ad3723d1859c2bd0216facab79 Mon Sep 17 00:00:00 2001
From: Rolf Kristensen <snakefoot@users.noreply.github.com>
Date: Sun, 28 Mar 2021 22:28:46 +0200
Subject: [PATCH] NLogAspNetCoreOptions - Added ReplaceLoggerFactory and
 RemoveLoggerFactoryFilter (#657)

---
 src/NLog.Web.AspNetCore/AspNetExtensions.cs   | 19 ++++++++++++++++++-
 .../AspNetCoreTests.cs                        | 18 +++++++++++++++++-
 2 files changed, 35 insertions(+), 2 deletions(-)

diff --git a/src/NLog.Web.AspNetCore/AspNetExtensions.cs b/src/NLog.Web.AspNetCore/AspNetExtensions.cs
index ac57f1a7..bd78f479 100644
--- a/src/NLog.Web.AspNetCore/AspNetExtensions.cs
+++ b/src/NLog.Web.AspNetCore/AspNetExtensions.cs
@@ -312,7 +312,24 @@ private static void AddNLogLoggerProvider(IServiceCollection services, IConfigur
             ConfigurationItemFactory.Default.RegisterItemsFromAssembly(typeof(AspNetExtensions).GetTypeInfo().Assembly);
             LogManager.AddHiddenAssembly(typeof(AspNetExtensions).GetTypeInfo().Assembly);
 
-            services.TryAddEnumerable(ServiceDescriptor.Singleton<ILoggerProvider, NLogLoggerProvider>(serviceProvider => factory(serviceProvider, configuration, options)));
+            var sharedFactory = factory;
+
+            if ((options ?? NLogAspNetCoreOptions.Default).ReplaceLoggerFactory)
+            {
+                NLogLoggerProvider singleInstance = null;   // Ensure that registration of ILoggerFactory and ILoggerProvider shares the same single instance
+                sharedFactory = (provider, cfg, opt) => singleInstance ?? (singleInstance = factory(provider, cfg, opt));
+
+                services.AddLogging(builder => builder?.ClearProviders());  // Cleanup the existing LoggerFactory, before replacing it with NLogLoggerFactory
+                services.Replace(ServiceDescriptor.Singleton<ILoggerFactory, NLogLoggerFactory>(serviceProvider => new NLogLoggerFactory(sharedFactory(serviceProvider, configuration, options))));
+            }
+
+            services.TryAddEnumerable(ServiceDescriptor.Singleton<ILoggerProvider, NLogLoggerProvider>(serviceProvider => sharedFactory(serviceProvider, configuration, options)));
+
+            if ((options ?? NLogAspNetCoreOptions.Default).RemoveLoggerFactoryFilter)
+            {
+                // Will forward all messages to NLog if not specifically overridden by user
+                services.AddLogging(builder => builder?.AddFilter<NLogLoggerProvider>(null, Microsoft.Extensions.Logging.LogLevel.Trace));
+            }
 
             //note: this one is called before  services.AddSingleton<ILoggerFactory>
             if ((options ?? NLogAspNetCoreOptions.Default).RegisterHttpContextAccessor)
diff --git a/tests/NLog.Web.AspNetCore.Tests/AspNetCoreTests.cs b/tests/NLog.Web.AspNetCore.Tests/AspNetCoreTests.cs
index 935fc0d3..0d8edf0c 100644
--- a/tests/NLog.Web.AspNetCore.Tests/AspNetCoreTests.cs
+++ b/tests/NLog.Web.AspNetCore.Tests/AspNetCoreTests.cs
@@ -54,6 +54,22 @@ public void UseNLogShouldLogTest()
             Assert.Equal("logger1|error1", logged.First());
         }
 
+#if !ASP_NET_CORE1
+        [Fact]
+        public void UseNLog_ReplaceLoggerFactory()
+        {
+            var webhost = CreateWebHost(new NLogAspNetCoreOptions() { ReplaceLoggerFactory = true });
+
+            // Act
+            var loggerFactory = webhost.Services.GetService<ILoggerFactory>();
+            var loggerProvider = webhost.Services.GetService<ILoggerProvider>();
+
+            // Assert
+            Assert.Equal(typeof(NLogLoggerFactory), loggerFactory.GetType());
+            Assert.Equal(typeof(NLogLoggerProvider), loggerProvider.GetType());
+        }
+#endif
+
 #if !ASP_NET_CORE1 && !ASP_NET_CORE2
         [Fact]
         public void LoadConfigurationFromAppSettingsShouldLogTest()
@@ -235,7 +251,7 @@ private static ILoggerFactory GetLoggerFactory(IWebHost webhost)
             return webhost.Services.GetService<Microsoft.Extensions.Logging.ILoggerFactory>();
         }
 
-#if !ASP_NET_CORE2 && !ASP_NET_CORE3
+#if ASP_NET_CORE1
         public class Startup
         {
             public Startup()